The invention relates to a device for evaporating a liquid, in particular an air freshener or an insecticide.
A device for evaporating liquids is known from European patent application EP 1 108 358 A1. This device has a housing in which a supply container is mounted that is filled with the liquid to be evaporated. A wick immerses in the supply container. This wick protrudes from the container, and a ring-shaped heating element is associated with the wick. So that the rate of evaporation can be adjusted, the heating element is retained in a sliding carriage that comprises two arms opposing one another. These arms penetrate slot-like openings of the housing and project beyond the outer contour of the housing. In this way, the heating element can be axially displaced in relation to the wick to adjust the evaporation rate accordingly. However, adjustments in low evaporation rates are very inaccurate.
The invention is designed to provide a device of the type specified above which has evaporation rate that can be accurately adjusted in a simple and delicate manner.
The invention relates to a device for evaporating a liquid. The device can be used as an air freshener or a distributor of insecticides, which are preferably used in closed rooms. The liquid itself is contained in a container that is supported in a housing of the device. A wick is immersed in this container. This wick preferably protrudes from the top side of the container. The wick can be formed of plant fibers such as cotton. Alternatively, the wick can be formed from porous ceramics and a multitude of thin glass fibers. It is important that the wick have an adequately strong capillary effect to draw the liquid from the container.
To increase the evaporation effect of the liquid aspirated by the wick, a heating element is associated with the wick that heats the wick preferably by means of heat radiation or convective heat transfer. The preferred temperature of the wick is approximately 80xc2x0 C., whereby the evaporation rate rises higher proportionally with the temperature of the wick. This means that the evaporation rate is dependent not only on the heating output of the heating element, but also upon the ambient temperature in the room. Moreover, it is necessary to adapt the evaporation rate of the liquid to the given size of the room, as well as to the individual preferences of the people present in the room.
It is also possible to vary the output generated by the heating element, so that the heating element is designed in the form of an electrical heating system. However, the cost of electronic components required for this purpose is economically not justifiable especially if the device is operated connected to a power main. For this reason, the heating element is arranged so that it can be adjusted in relation to the wick. Depending on the mutual position between the heating element and the wick, a higher or lower proportion of the heating output which comes from the heating element is received by the wick, so that the evaporation rate of the liquid can be adjusted in this manner.
The heating element is fixedly supported in the housing and the container with the wick is retained on a sliding part. It is necessary to displace the container with the liquid contained therein even though the container is heavier than the wick. However, this arrangement offers the advantage that no electric cables for the heating element have to be moved when the evaporation rate is adjusted. In this way, the adjustment of the evaporation rate is not obstructed by the cables leading to the heating element, which permits a particularly delicate and therefore precise adjustment of the evaporation rate. The container fits the housing with the sliding part in any position and the sliding part can be displaced relative to the housing. However, the sliding part is guided via a torsional movement of a rotating knob. The container can be shaped in this way in any desired form and does not need to be designed in the form of a rotation-symmetrical body. This permits the use of a very wide spectrum of different designs for the container, so that it is possible to obtain an attractive design of the device, including the associated container without technical limitations.
To assure a delicate adjustment of the evaporation rate of the liquid, the container or heating element should be actively connected with an actuation element via a non-linear transmission. It is possible to adapt the transmission ratio between the actuation element, which can be adjusted by hand, and the container or the heating element to the given requirements.
In the range of lower evaporation rates, the transmission preferably has a more delicate transmission ratio than in the range of high evaporation rates. Thus, the container and the heating element can be adjusted in the range of low evaporation rates with a large spacing from each other, providing the transmission with substantially higher precision than with high evaporation rates, where any delicate (or fine) adjustment is unimportant.
Because the actuation element is in the form of a rotary knob, this design permits a simple and at the same time ergonomic adjustment of the evaporation rate. In addition, a rotary knob can be adjusted with substantially greater precision than, for example a sliding part.
A pin which is eccentrically retained on the rotary knob in relation to its axis of rotation provides a simple transmission. This pin transmits the motion of the rotary knob to the sliding part supported on the housing, with the container or the heating element being supported on this sliding part. Thus, the housing has a preferably kidney-shaped breakthrough or hole, which is penetrated by the pin to not obstruct its movement. The pin along with the hole of the sliding part forms an eccentric transmission wherein the pin translates the rotational movement of the rotary knob into a sliding movement in a nonlinear manner.
The hole of the sliding part extends approximately transversely to the sliding direction of the sliding part. Thus, the pin can be adjusted without obstruction in a transverse direction to the sliding direction of the sliding part when the rotary knob is turned. In the sliding direction, the hole is preferably adapted to the cross section of the pin, so that the rotational movement of the rotary knob is precisely transmitted to the sliding part.
To maintain a correct radial alignment of the heating element with the wick, it is important to axially guide the sliding element in relation to the wick or heating element. For this purpose, the housing has at least one guide rail on which the sliding part is guided.
To retain the container in an adequately safe manner, the sliding part or the housing should have a clip-like retaining element. Such a clip allows the container to be exchanged after the liquid contained in the container has been evaporated.